The present invention relates to an audio output amplifying device.
A balanced transformerless amplifier (hereinafter referred to as a BTL amplifier when applicable) is well known in the art as an audio output amplifying device. In the BTL amplifier, two SEPP (Single-Ended Push-Pull) amplifiers are connected in parallel to a power source and in series with a load so that a high output can be obtained with a relatively low supply voltage. It is generally not economical to use a BTL amplifier, however, for a load which can be sufficiently driven with a small amount of electric power. Sometimes it is preferable to allow two SEPP amplifiers forming a BTL amplifier to drive two loads because the resulting audio device can be reduced in circuit complexity and size.
It goes without saying that, in manufacturing a plurality of audio amplifying devices, including such an audio output amplifying device, which are different in circuitry, economical use of a single audio output amplifying device for a plurality of such audio devices is preferable.